Life's great Mysteries - Can a venomous snake commit suicide by biting itself?

Come on… you have to admit you’ve wondered this, right? First, let’s figure out how venomous snakes can even live at all, considering a deadly venom is inside their body. It’s important to understand the difference between venom and poison. Generally, poison is something that has ill effects when you ingest it, or when it gets on your skin. For example, some toads are poisonous because they secrete a substance that is harmful if swallowed. Venom, on the other hand, is harmful when it gets injected into your bloodstream. Snake venom is only toxic when it gets into your blood. You can think of a rattlesnake’s fangs as syringes for injecting their venom.

Well, snakes store their venom inside special glands, which keep the venom from entering their blood system, thus protecting them. When a rattlesnake bites its prey, the prey animal dies, and the snake can swallow it whole. So, the venom ends up in the snake’s digestive system, but venom cannot get into the snake's blood from inside the stomach or intestines.

But what if a snake bites itself? Usually, nothing dramatic happens, but sometimes it can be deadly. In other words, there's not a simple answer. Venomous snakes show a variety of different ways to protect themselves from their own bites. Some work better than others, and they work differently in different parts of their bodies.

You know how curious scientists are, right? Well, many scientists have studied this by, well… injecting snakes with their own venom. Ethical issues aside, scientists have learned a great deal about this. It turns out different snakes have many different types of venoms, with many different damaging effects (nerve damage, circulatory system damage, and local tissue damage… nasty stuff).

Animal bodies, including humans, have all kinds of defenses to help prevent damage. Let’s think of these defenses as locks. They lock out the bad venom. Venoms contain substances that we can think of as keys to these locks. The keys unlock the defenses and cause harm. There are many types of locks, and many different keys. Each key works in some locks but not in others. It’s complex.

Here’s an example: Neurotoxins are positively charged, so they’re attracted to negatively charged parts of receptor proteins on nerves. This way, they “unlock” the defenses of the nerves and cause damage. Well, some snakes protect themselves from their own neurotoxin by reversing the polarity of their own nerve receptors. So, their positively charged neuroreceptors repel their own positively charged toxins, thus protecting them from their own venom. Cool, huh?

But this is only one example of a gazillion different locks and keys. So, sometimes, a snake can seriously harm or even kill itself by biting its own body. Also, different individual snakes of the same species can have variations in their locks and keys, which is why, in one 1932 study, scientists made a couple of black-tailed rattlesnakes bite each other, and both snakes died as a result.

Usually, though, if a venomous snake accidentally bites itself, it can relax and casually slither away, saying, “I meant to do that.”

Below is a venomous eyelash viper Trish and I found in Costa Rica.